Conventionally, a scroll compressor has been known as a compressor for compressing fluid. In the scroll compressor, a fixed scroll and a movable scroll are engaged with each other, thereby forming a compression chamber between the fixed scroll and the movable scroll. As the compression chamber moves from the periphery toward the center in association with eccentric rotation of the movable scroll, the volume of the compression chamber is gradually decreased. Fluid is compressed in the course of decreasing the volume of the compression chamber.
In the scroll compressor, the pressure of fluid of the compression chamber acts on the movable scroll as separating force for separating the movable scroll from the fixed scroll. Thus, it is necessary that pressing force for pressing the movable scroll against the fixed scroll is provided to the movable scroll. Japanese Patent Publication No. S58-122386discloses a scroll compressor including a mechanism for pressing a movable scroll against a fixed scroll. In the scroll compressor, back-pressure holes are formed in an end plate of the movable scroll, and a back-pressure chamber is formed so as to face a back surface of the end plate of the movable scroll. The back-pressure holes open to a compression chamber which is in the course of compressing fluid. Intermediate-pressure fluid is introduced into the back-pressure chamber.